Gram Negative Rods

Question 1

How do we tell the difference between salmonella and shigella?

Answer 1

SS agars (Salmonella Shigella agar)

Salmonella turns black while shigella turns yellow

Both are not able to ferment lactose so we can’t use that!

Question 2

Which bacteria is famous for causing the Black or Bubonic Plague?

Answer 2

Yersinia

Question 3

What is the name of the enterotoxin produced by shigella?

Answer 3

Shiga toxin which kills epithelial cells and rarely invades bloodstream

Question 4

What are the 2 unique characteristics of Yersinia?

Answer 4

Weird staining pattern - “safety pin stain”

Transported by a vector (fleas… On rats)

Question 5

Virulence factors of Yersinia

Answer 5

Capsule
2 proteins - V antigen and W antigen
Murine (mouse) toxin

Question 6

What is a sylvatic plague?

Answer 6

Disease that is passed from wild animal to wild animal

Question 7

Which is the only country unaffected by the plague?

Answer 7

Australia

Question 8

Where does the Yersinia pestis live inside humans once transferred?

Answer 8

Macrophages try to eat it, they die, go to the lymph nodes and that is where the Yersinia pestis ends up living, dividing and creating necrotic tissue

Question 9

What are buboes?

Answer 9

Enlarged lymph nodes that are infected by dividing Yersinia pestis, tissue becomes necrotic and BLACK (Black Death) and could rupture. Ew.

Question 10

How can the bubonic plague be transferred between humans?

Answer 10

Pneumonic plague can be transferred to other humans (it’s also fatal in a few days)

Question 11

What is unique about Shigella’s motility?

Answer 11

Genes are turned on INTRACELLULARLY to grow an actin tail so that it can move cell to cell